As someone who works for a major accounting firm, I think that unless you have a frum interviewer, the person will likely be put off by a not well kept beard. i know it sounds silly, but maybe ask your rav if he thinks its better to shape your beard rather than shave it off fully.
the most important thing to think about when it comes to these interviews is to show why you are different than the rest of the applicants who all have the same background and good grades.
good luck